050 FXUS66 KOTX 200809 AFDOTX Area Forecast Discussion National Weather Service Spokane WA 109 AM PDT Fri Jun 20 2025 .KEY MESSAGES... - Big pattern change heading into the weekend with much cooler temperatures and rain showers. - Chance of thunderstorms over the northern mountains Friday, Sunday, and Monday && .SYNOPSIS... A pattern shift arrives Friday into the weekend delivering much cooler temperatures and rain showers. In addition, there will be a chance of thunderstorms over the northern mountains at times Friday through Monday. && .DISCUSSION... Today through Monday: A big pattern change is coming is a large closed low barrels through the region. This morning the low is off the Washington coast with a band of showers developing across Central Idaho. Models continue to depict this area expanding this morning with rain showers expect to move into the Camas Prairie and Central Panhandle Mountains, possibly extending as far west as Moscow and Lewiston. For this afternoon as the low moves into SW WA/NW OR the atmosphere will become increasingly unstable over North Central WA courtesy of afternoon sunbreaks and cooling aloft with the incoming low. The NBM continue to advertise a 20-30% chance of thunderstorms for the Okanogan and Methow Valleys and surrounding high terrain, as well as areas near the Canadian border. The cold advection with the low will also lead to breezy winds especially in Central WA. Tonight the low tracks along the WA/OR border before rapidly pushing into NW Montana on Saturday. Models continue to show the highest regional POP`s on Saturday as moisture wraps around the backside of the low into Eastern Washington and North Idaho. On Sunday and Monday as the low moves out, the region remains under the influence of a long wave trough with additional impulses dropping into the region. Afternoon heating combined with some lift from these will kick off another round of showers, but with better instability as well with the ECMWF advertising 500-1000 J/KG of surface based CAPE over the northern mountains. Ensembles are painting a rather wet scenario this weekend for the northern mountains, with a 80-90% chance of at least 0.50" of rain for Colville and Sandpoint. Here are the latest NBM 72 hour probabilities of precipitation amounts receiving various thresholds ending 5 AM Monday: City .10+" .25+" .50+" 1.00+" 1.50+" Spokane 90% 75% 45% 10% 0% Omak 95% 90% 70% 20% 5% Colville 100% 95% 85% 35% 5% Sandpoint 100% 95% 90% 65% 40% Wenatchee 60% 20% 5% 0% 0% Moses Lake 60% 35% 15% 0% 0% Pullman 80% 50% 10% 0% 0% Lewiston 80% 40% 5% 0% 0% Tuesday through Thursday: Ensembles are in good agreement that warmer and drier conditions develop as a short wave ridge moves over the region Tuesday and Wednesday. Will have to watch a potential short wave dampening the ridge on Thursday which may produce a few showers especially near the Cascade crest and along the Canadian border but confidence is low. JW && .AVIATION... 06Z TAFS: VFR conditions are expected to continue for all TAF sites through 06z Saturday. Winds will start to pick up in the lee of the Cascades after 06z with speeds at KEAT around 15-20 kts. A band of precipitation will form over northeast OR around tonight and move north towards KLWS-KCOE bringing a 20-40% chance for showers between 12z-20z. KPUW-KGEG- KSFF have a 10-20% chance to get brushed by this round of showers. Friday afternoon instability showers will be on the increase around the region, but remaining isolated/scattered in coverage over most areas outside of the mountains. There is also a 20% chance of afternoon thunderstorms for Chelan, Winthrop, Omak, Republic, and the surrounding mountains. FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: High confidence for VFR conditions through 06z Saturday. JW ----------------------- Confidence descriptors: Low - Less than a 30 percent chance Moderate - 30 to 70 percent chance High - Greater than a 70 percent chance For additional probabilistic information for NWS Spokane airports, please refer to the Aviation Dashboard on our webpage: https:/www.weather.gov/otx/avndashboard && .Preliminary Point Temps/PoPs... Spokane 68 45 57 46 66 48 / 20 20 70 60 50 40 Coeur d`Alene 67 44 55 44 64 49 / 40 40 80 80 60 50 Pullman 62 43 57 42 62 42 / 30 20 40 60 50 20 Lewiston 71 48 67 50 70 51 / 40 30 30 60 50 10 Colville 69 45 56 44 64 39 / 60 70 100 80 90 70 Sandpoint 65 45 54 44 62 48 / 50 70 100 90 80 80 Kellogg 61 42 51 45 59 49 / 70 50 80 90 70 50 Moses Lake 73 48 66 49 74 50 / 20 20 50 40 40 20 Wenatchee 70 52 66 52 73 53 / 30 30 50 40 40 10 Omak 73 46 64 48 71 49 / 80 80 80 70 70 40 && .OTX WATCHES/WARNINGS/ADVISORIES... WA...None. ID...None. && $$